1. Field of the Invention
The present invention relates generally to a broadband wireless communication system. More particularly, the present invention relates to an apparatus and a method for mitigating inter-cell interference in a broadband wireless communication system.
2. Description of the Related Art
A conventional wireless communication system performs resource allocation and power control based on a single cell without considering inter-cell interference. For doing so, a concept of network utility is introduced as an object function of the entire system. The network utility is a function considering not only the system throughput but also the fairness, and, for example, is given by Equation 1.
                              U          ⁡                      (                          R              m                        )                          =                  {                                                                                                                1                                              1                        -                        α                                                              ⁢                                          R                      m                                              1                        -                        α                                                                              ,                                                                                                                        if                      ⁢                                                                                          ⁢                      α                                        >                    0                                    ,                                      α                    ≠                    1                                                                                                                                            log                    ⁢                                                                                  ⁢                                          R                      m                                                        ,                                                                                                  if                    ⁢                                                                                  ⁢                    α                                    =                  1                                                                                        [                  Eqn          .                                          ⁢          1                ]            
In Equation 1, U(Rm) denotes the network utility of a User Equipment (UE) m, Rm denotes a data rate of the UE m, and α denotes a fairness regulation factor.
By maximizing the sum of the network utilities of a plurality of UEs, the system throughput is maximized. In that regard, the determination of a network utility vector to maximize the sum of the network utilities is referred to as Network Utility Maximization (NUM).
While the system throughput can be optimized by determining the NUM, this solution merely takes account of the single-cell environment. In a multi-cell environment, a UE traveling in the cell boundary suffers from communication interruption caused by interference of a neighboring cell, and the performance expected based on the result of the NUM is not attained. Thus, a NUM scheme based on the multi-cell environment is considered. However, a method for determining an optimum solution in a multi-cell environment is not yet known, and the solution, if any, will require very complicated computations. Moreover, to address the NUM scheme based on the multi-cell environment, it is necessary to share channel information between Base Stations (BSs) managing respective cells and UEs, which demands considerable control overhead. In this regard, there is a need for a method for addressing the NUM scheme considering the multi-cell environment, to lower the computational complexity, and to minimize the control overhead.